Patent GB-1093422-A (GB)
Title: Process for the manufacture of polyamide filaments having a low tendency to shrink
Inventor: SPECKER HUGO
IPC: D02J1/22
Filed: 1964-01-28
Abstract: 1,093,422. Stretching and relaxing polyamide filaments. SOCIETE DE LA VISCOSE SUISSE. Dec. 17, 1964 [Jan. 28, 1964], No. 3710/64. Heading B5B. [Also in Division F2] A roller comprises three coaxial sections the diameters of which successively decrease, the section of greatest diameter and part of the section of least diameter being provided with cooling means, and the intermediate section and part of the section of least diameter adjacent the section of intermediate diameter being provided with heating means such that the temperature of the surface of part of the section of least diameter can be kept higher than that of the surface of the section of intermediate diameter. It is preferred that the section of least diameter has a diameter from 10 to 15% less than the diameter of the section of greatest diameter and that the section of intermediate diameter has a diameter greater than the diameter of the section of least diameter by about one-third of the difference between the diameters of the sections of greatest and least diameter; the diameters may be 100 Œ 5 mm., 91 Œ 4 mm. and 87 Œ 4 mm. for the sections of greatest, intermediate and least diameter, respectively. Fig. 3 illustrates the roller with an associated feed roller 5. The roller 6B, which is attached to spindle 16 by thermal insulation 17, comprises an externally polished roller body 18 which carries on thermal insulation 21 a polished metal ring 22 which forms the section of largest diameter, which may be internally cooled by circulating air and which may additionally be provided with radial bores (not shown) to improve air circulation. A cavity 19 in the roller body may contain an electric heater 20 by which the section 23 of intermediate diameter and portion 24 of the section of least diameter adjacent thereto may be heated. Open end portion 25 of the section of least diameter is provided with radial cooling bores and internal cooling ribs 26. In an embodiment illustrated in Fig. 2 (not shown), the section of greatest diameter comprises a collar of plastics material secured to the roller body in place of the metal ring, the collar being resistant to wear and a poor conductor of heat. As illustrated in Fig. 1 (not shown), the roller may form the stretching roller in a stretchtwisting frame, yarn passing from a bobbin via a yarn guide, a supply device consisting of a pair of rollers, and a stretching pin, on to a draw-off unit consisting of a feed roller and the roller of the invention from which the yarn passes via a further yarn guide to be twisted by a traveller on a ring twisting spindle and finally to be reeled on a further bobbin. The roller may be used in modifying polyamide (for example polyhexamethylene adipamide or polycaprolactam) filaments to impart thereto a low and uniform tendency to shrink, the filaments being passed around the roller in order initially to be stretched and then to be relaxed. The filaments are passed first at a temperature of at most 110‹ C. round the section of greatest diameter, then round the section of intermediate diameter and a portion of the section of least diameter adjacent the section of intermediate diameter, and finally around the cooled portion of the section of least diameter, the temperature of the section of intermediate diameter being from 120‹ to 200‹ C., and the temperature of the portion of the section of least diameter adjacent the section of intermediate diameter being from 130‹ to 210‹ C. and at least 10‹ C. (preferably from 10‹ to 50‹ C.) higher than the temperature of the section of intermediate diameter. The filaments may move 2 to 4 times, once or twice, 3 to 8 times and 2 to 5 times round the section of largest diameter, the section of intermediate diameter, the portion of the section of least diameter adjacent the section of intermediate diameter and the cooled portion of the section of least diameter, respectively.